Dental casting apparatus.



W. B. G. KAISER. 5 DENTAL CASTING APPARATUS.

APPLICATION FILED SEPT. 2, 1913.

1,1 15,678. Patented Nov. 3, 1914.

2 SHEETS-SHEET 1.

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W. B. G. KAISER. DENTAL CASTING APPARATUS. APPLICATION FILED SEPT. 2. 1913- 1,1 15,678. Patented N0v.3,1914.

2 SHEBTSSHE11T Z.

I. f f l 3 DENT-AL cAsrI'Nie APPARATUS.

Specliication of Letters Patent. v "Application filed September 2:, 1913. Serial No. 787,707.

wI LmAm' BoLIvAa CARL n rsiinor BAMBuaG, GERMANY.

i To all whom it may mm Be it known that, I, WILLIAM BOLIVAR CARL KAISER, a subject and resident of Hamburg, in the-German Empire, have invented new and a useful Improvements in Dental Casting-Apparatus, of whichthe following is aspecification. L p

The presentinvention relates to improvements in apparatus for the production of teeth-plugs, stoppings 6r fillings composed of china, porcelain or similar material, and has for its objects to provide anarrangement which will enable such plugs, stoppings or fillings to be produced "in a simple and economical manner.

Hitherto known casting the molten filling material was forced into the mold by suction cannot be used for manufacturing fillings of porcelain onaccount of the high melting temperature of the porcelain and on account of the difiiculty of producing an absolute tight joint between the moldand the suction pipe, which could Withstand the great heat. For this reason fillings of porcelain have'hitherto been made in; a platinum-foil, shaped to the cavity of thetooth, the porcelain material being applied repeatedly and then burnt each time, until the platinum-foil is filled up to the proper degree. This method of course is very tedious and expensive.

Inthe device for producing porcelain fillings, forming the subject of the present invention, a mold carrying tube is arranged in the melting'chamber of an felectric furnace. The mold carrier, which is connected with a suction pipe, projects with its upper end into the (casting) mold provided with air ducts and 1s firmly embraced by the mold.

Byreason of the arrangement of the mold directly within the melting chamber of the meltin furnace, the heat is taken advantage of to t e greatest possible degree, and since the moldincloses the carrier tube, the contractionof the mold, which is unavoidable at such great heat and which heretofore caused leakages at the joint, between the mold and the suction pipe, is in this case not ,only harmless but assists in improvingthe closeness of the joint, so that failures on account.

of insuficient sucking power. are always avoided. The mold carrying tube 1s prodevices in which jcan be created in any known manner.

ing into the casin f'platinum tube Z, w ich forms the mold carrier and which at a certain distance froni its upper end is provided with a disk shaped flange m, also of platinum. A U-shaped fhoop 'n. 1sfastened to the flangeam and serves as a handle for the mold carrying vmantle forms the mold chest.

I In the drawings two modes of construcftionpf the apparatus are shown.

Figure 1 is a vertical section of an electric furnace and-one form of casting apparatus. ZFlg. 2 is an elevation of one form of a model ;;for producing the mold for the plug or fillvided with a flange, which together with a Patented. Nov. 3, 1914.. I

'ging. Fig. 3 is an elevation, partly in sec- ;-tion, of the mold chest seen at right angles gm; Fig. 1. Fig. 4 is a horizontal section of ;F1g. 3. Fig; 5 is a vertical section of a ,modified form ofmold chest showing a mold formed therein, and Fig. 6 is a partial elevation of the moldrchest shown in Fig. 5

iand mounted in an electric furnace which is 'Sh0WI1 in section.

I The electric furnace consists of a casing or cylinder at having a hinged cover 6. Both fparts are provided with a lining 0 and (Z respectively, of refractory material. The latter is heldapa'rt from the metal by a @layer 0 of asbestos for preventing loss of 'heat. Within the wall of the cylindrical -melting chamber 1 an electric'spirally shaped heating wire is embedded, the ends of Which ,are fastened to binding screws 9. Into the bottom of the casing or cylinder (1. projects {asuction pipe or tube 2', which'is provided with a cock J21 and which is in connection 'with a tank or vessel 7,4, in which a vacuum Into the upper end of the suction pipe 11 project-. a is screwed a conical tube Z. To procure the mold of plaster of Paris two semi-cylindrical troughs 0, (Figs.

3 and 5) are used, which are placed upright :onthevflange m in such manner that they abut against the legs'of the hoop n and to-v gether with the same form a mold-chest, the

bottom of which is formed by the flange m. A mantle p embracin the two semi-cylindrical halves 0 holds t e parts together.

.When a plu or filling is to be produced the model of t e filling (Fig. 2) formed in a knownmanner of a wax body g and wires l r, are placed into the mold-chest in such manner, that the lower and longer wire 7- is placed in the axis of the mold carrying tube Z and the wax body 9 is situated somewhere about half the height of the mold chest. The mold carrying tube is previously filled with a mixture of a paste of plaster of Paris v and asbestos wool, which when hardened holds the model in the proper position. Plaster of Paris is then run into the troughs and as soon as the plaster of Paris has hardened the wires 1" are withdrawn and also the semi cylindrical troughs 0 are removed. The laster of Paris is thereby firmly attache with the mold carrying tube on account of its conical shape. The latter is now brought into the melting chamber of the furnace and screwed down into the upper end of the suction pipe 2', the hoo n serving as a handle. On the top of the mo d a pieceof plprcelain is placed and the cover I) finally s ut.

When the electric current is closed not only the heating wire f, but also the wall of the chamber is heated to white heat. The intense heat acting directly on the mold and on the porcelain causes the latter to melt into a sufliciently fluid state, so that, when the cock h is opened the vacuum sucks the liquid porcelain down into the mold, the wax body 9 having been completely absorbed in the meantime. The lower channel formed by the lower wire 9" holding the wax body 9 can be omitted altogether. As above described, the mold carrying tube Z is filled with a mixture of paste, of plaster of Paris and asbestos wool which when hardened holds the mold in the proper position. By placing the wax body 9 on the top of the described hardened mixture in the carrying tube and forming the moldby pouring plaster of Paris into the mold-chest, then after the plaster of Paris is hardened, the one wire projecting on top being pulled out, and therefore, having used no lower wire, there will be no channel within the mixture of plaster of Paris and asbestos in the tube Z so that there can be no fear of the molten casting material passing down the tubes Z and Z. But-even if the lower wire 1' is used the temperature within the lower part of the furnace will not be suflicient to allow the molten material to run down the full length of the channel formed by the lower wire 1'. The molten material may enter the channel, which opens out into the hollow of the mold proper after the wax has been melted and sucked up by the surrounding plaster of Paris, but it will not run as far as the lower end of this channel for the reason that the temperature decreases toward the outer surface of the fur- The temperature necessary for melting porcelain is extremel high and great difficulty is met with to o tain this temperature, and it is evident that the temperature may be obtained in the very center of the furnace while at the lower end it is insufficient for keeping the porcelain in a, molten state.

In the construction shown in Figs. 5 and 6 the mold carrying tube Z is provided at its upper end with aflange m and into said tube is screwed a special tube 8 made of chamotte, hard-porcelain, quartz or other refractory material. This special tube previously filled by a paste of plaster of Paris and asbestos fibers will be embraced by the mold in producing the same. The advantage of making use of such a special tube is that the expensive platinum may be avoided and this construction has a further advantage inasmuch as the flange will not be subjected to the direct action of the heat of the melting chamber. To obtain this advantage the melting chamber of the melting furnace is made open at the bottom, so that the tube Z carrying the mold when introduced from above projects through the bottom of the melting furnace and is finally screwed to the suction pipe 71'. The flange m is then situated below and outside of the melting chamber the opening being covered by two semicircular cover plates 25. The troughs 0 forming the mold chest are provided on the bottom at the inner wall with a groove 11., by which the troughs 0, being held together by the mantle p, embrace the flange m to produce a good hold. The last described construction has the advantage, that the semicylindrical halves of the mold chest are firmly and tightly connected with the flange.

I claim:

1. In a dental casting apparatus, a mold support comprising two tubes, one of which is inserted in the other, a flange on one of the tubes for supporting the mold, one of said tubes also projecting into the mold.

2. In a. dental casting apparatus, a mold support comprising a tube adapted to carry the casting mold, a second tube made of refractory material and adapted to be inserted into the first named tube at one end, and project into the mold with its other end, one of the tubes being provided with a flange to support the mold.

3. A dental casting apparatus, comprising an electric furnace open at its lower end, a tube to carry the casting mold, a. second tube made of refractory material adapted to be inserted into the first named tube at one end and into the mold with its other end, a flange on the first named tube being outside of the furnace when the mold is inserted.

4. In a dental casting apparatus, a mold support comprising a tube having a. flange to support the mold, and a model supporting tube made of-refractory material having one end inserted in the mold supporting tube and the other end adapted to project into the body of the mold.

5. In a dental casting apparatus, the combination of a mold support, comprising two tubes, one of which is inserted in the other, a flange on one of the tubes for supporting the mold, one of said tubes projecting into the mold, and a removable mold chest comprising two semi-cylindrical troughs mount- 10 ed on the flange, and a mantle adapted to embrace said troughs to hold the latter together during the formation of the mold.

WILLIAM BOLIVAB CARL KAISER. 

